This invention relates to methods and complexes for forming metal-containing films, such as metal or metal alloy films, particularly during the manufacture of semiconductor device structures. The complexes preferably include low valent metal, and are particularly suitable for use in a chemical vapor deposition system.
High quality thin oxide films of metals, such as barium-strontium-titanates and strontium-bismuth-tantalates deposited on semiconductor wafers have recently gained interest for use in memories (e.g., dynamic random access memory (DRAM) devices, static random access memory (SRAM) devices, and ferroelectric memory (FE RAM) devices). These materials have very high dielectric constants and excellent resistance to fatigue. They also have suitable properties for a variety of other uses, such as electrooptic materials, pyroelectric materials, and antireflective coatings.
Suitable metal oxides are typically delivered to a substrate in the vapor phase; however, many oxides are difficult to deliver using vapor deposition technology. Many precursors are sensitive to thermal decomposition. Also, many precursors have vapor pressures that are too low for effective vapor deposition. For example, molecules containing certain low-valent metals, such as barium, tend to aggregate, which causes poor volatility. Thus, there is a continuing need for methods and materials for the deposition of oxide films using vapor deposition processes on semiconductor structures, particularly random access memory devices.
The present invention provides complexes and methods for forming metal-containing films, particularly low-valent metal-containing films, on substrates, such as semiconductor substrates or substrate assemblies during the manufacture of semiconductor structures. The methods involve forming a metal-containing film using a complex containing one or more chelating oxygen- and/or nitrogen-donor ligands. The metal-containing film can be used in various metallization layers, particularly in multilevel interconnects or dielectric layers, in integrated circuit structures.
The metal-containing film can be a film of a single metal, or it can be a metal alloy containing a mixture of metals, or a metal or mixture of metals with one or more metalloids. Furthermore, for certain preferred embodiments, the metal-containing film can be an oxide, nitride, sulfide, phosphide, arsenide, stibnide, selenide, silicilide, or combinations thereof.
Thus, in the context of the present invention, the term xe2x80x9cmetal-containing filmxe2x80x9d includes, for example, relatively pure films of main group metals, transition metals, or lanthanides, alloys of these metals, as well as complexes of metals or metal alloys with other elements (e.g., O, N, S, Si, P, As, Sb, and Se), or mixtures thereof. The term xe2x80x9csingle metal filmxe2x80x9d refers to relatively pure films of single metals. The term xe2x80x9cmetal alloy filmxe2x80x9d refers to films of these metals in alloys with or without other metals or metalloids, for example.
One preferred method of the present invention involves forming a film on a substrate, such as a semiconductor substrate or substrate assembly during the manufacture of a semiconductor structure, by: providing a substrate (preferably, a semiconductor substrate or substrate assembly); providing a precursor composition comprising one or more complexes of the formula: 
wherein: M is any metal (main group, transition metal, lanthanide); each Y group is independently O or Nxe2x80x94R3; L is a neutral or or anionic (e.g., monoanionic or dianionic) supporting ligand; each R group is independently H, or an organic group; x=0 to 6 (preferably, 0 to 2); n+ is the oxidation state of the metal, which is typically 0 to +6; y=n if L is neutral, y=nxe2x88x92x if L is monoanionic, or y=nxe2x88x922x if L is dianionic; and forming a metal-containing film from the precursor composition on a surface of the substrate (preferably, a semiconductor substrate or substrate assembly). The metal-containing film can be a single metal film or an alloy film or an oxide, nitride, chalconide, etc. Using such methods, the complexes of Formula I are converted in some manner (e.g., decomposed thermally) and deposited on a surface to form a metal-containing film. Thus, the film is not simply a film of the complex of Formula I.
Complexes of Formula I are neutral complexes and may be liquids or solids at room temperature. If they are solids, they are preferably sufficiently soluble in an organic solvent or have melting points below their decomposition temperatures such that they can be used in flash vaporization, bubbling, microdroplet formation techniques, etc. However, they may also be sufficiently volatile that they can be vaporized or sublimed from the solid state using known chemical vapor deposition techniques. Thus, the precursor compositions of the present invention can be in solid or liquid form. As used herein, xe2x80x9cliquidxe2x80x9d refers to a solution or a neat liquid (a liquid at room temperature or a solid at room temperature that melts at an elevated temperature). As used herein, a xe2x80x9csolutionxe2x80x9d does not require complete solubility of the solid; rather, the solution may have some undissolved material, preferably, however, there is a sufficient amount of the material that can be carried by the organic solvent into the vapor phase for chemical vapor deposition processing.
Yet another method of forming a metal-containing film on a substrate, such as a semiconductor substrate or substrate assembly during the manufacture of a semiconductor structure, involves: providing a substrate (preferably, a semiconductor substrate or substrate assembly); providing a precursor composition comprising one or more organic solvents and one or more complexes of Formula I as defined above; vaporizing the precursor composition to form vaporized precursor composition; and directing the vaporized precursor composition toward the substrate to form a metal-containing film on a surface of the substrate. Herein, vaporized precursor composition includes vaporized molecules of precursor complexes of Formula I either alone or optionally with vaporized molecules of other compounds in the precursor composition, including solvent molecules, if used.
Thus, preferred embodiments of the methods of the present invention involve the use of one or more chemical vapor deposition techniques, although this is not necessarily required. That is, for certain embodiments, sputtering, spin-on coating, etc., can be used.
Methods of the present invention are particularly well suited for forming films on a surface of a semiconductor substrate or substrate assembly, such as a silicon wafer, with or without layers or structures formed thereon, used in forming integrated circuits. It is to be understood that methods of the present invention are not limited to deposition on silicon wafers; rather, other types of wafers (e.g., gallium arsenide wafer, etc.) can be used as well. Also, methods of the present invention can be used in silicon-on-insulator technology. Furthermore, substrates other than semiconductor substrates or substrate assemblies can be used in methods of the present invention. These include, for example, fibers, wires, etc. If the substrate is a semiconductor substrate or substrate assembly, the films can be formed directly on the lowest semiconductor surface of the substrate, or they can be formed on any of a variety of the layers (i.e., surfaces) as in a patterned wafer, for example. Thus, the term xe2x80x9csemiconductor substratexe2x80x9d refers to the base semiconductor layer, e.g., the lowest layer of silicon material in a wafer or a silicon layer deposited on another material such as silicon on sapphire. The term xe2x80x9csemiconductor substrate assemblyxe2x80x9d refers to the semiconductor substrate having one or more layers or structures formed thereon.
A chemical vapor deposition system is also provided. The system includes a deposition chamber having a substrate positioned therein; a vessel containing a precursor composition comprising one or more complexes of Formula I as described above; and a source of an inert carrier gas for transferring the precursor composition to the chemical vapor deposition chamber.
The present invention also provides certain complexes of Formula I. For complexes of Formula I wherein both Y groups are oxygen or NR3 groups, M is a main group metal selected from the group of Groups IA, IIA, IVA, and VA (i.e., Groups 1, 2, 14, and 15) metals or a transition metal selected from the group of Groups IB through VIIB (i.e., Groups 11, 12, and 3-7) metals. For complexes of Formula I wherein one Y group is oxygen and the other is an NR3 group, M is a main group metal, transition metal, or a lanthanide.
The present invention further provides precursor compositions containing one or more organic solvents and one or more, complexes preferably, two or more, of Formula I wherein M is selected from the groups of Ba, Sr, and Ti, or Bi, Sr, and Ta, or Bi, Sr, and Nb, and the compositions include at least two complexes containing different metals.